On Sat, Oct 28, 2023 at 8:44 PM Andrew Jones <ajo...@ventanamicro.com> wrote: > > On Sat, Oct 28, 2023 at 05:54:21AM -0300, Daniel Henrique Barboza wrote: > > The TCG emulation implements all the extensions described in the > > RVA22U64 profile, both mandatory and optional. The mandatory extensions > > will be enabled via the profile flag. We'll leave the optional > > extensions to be enabled by hand. > > > > Given that this is the first profile we're implementing in TCG we'll > > need some ground work first: > > > > - all profiles declared in riscv_profiles[] will be exposed to users. > > TCG is the main accelerator we're considering when adding profile > > support in QEMU, so for now it's safe to assume that all profiles in > > riscv_profiles[] will be relevant to TCG; > > > > - we'll not support user profile settings for vendor CPUs. The flags > > will still be exposed but users won't be able to change them. The idea > > is that vendor CPUs in the future can enable profiles internally in > > their cpu_init() functions, showing to the external world that the CPU > > supports a certain profile. But users won't be able to enable/disable > > it; > > > > - Setting a profile to 'true' means 'enable all mandatory extensions of > > this profile, setting it to 'false' means 'do not enable all mandatory > > extensions for this profile'. > > While this definition of profile=off looks appealing at first, it's really > just saying 'do not do anything', which means it's limiting the potential > of the property. But, I'll stop talking about this now, as I have another
This seems like the way to go to me > design suggestion instead: > > Since profiles are like G, and other shorthand extensions (just without an > official shorthand extension name), then I believe they should behave like > shorthand extensions. Also, since shorthand extensions can be derived from > their parts, then I think shorthand extensions should behave like > synthetic extensions. For example, zic64b starts 'false', but, at realize > time, if all its conditions are present, then it turns 'true'. Shorthand > extensions should be able to do that too by detecting that each of the > extensions they represent is present. > > So, I think we should automatically turn G and profiles (and future > shorthand extensions) on when all their respective extensions are present. I think that's a good idea and something we should support Alistair > > Thanks, > drew >
